Orthodontic treatment has become a widely accepted procedure in dentistry. The benefits include improved oral health, function, esthetics and quality of life. Significant disparities exist among income strata regarding access to orthodontic services. The sources of these disparities are complex and may reflect differences in the disease prevalence, gender, cultural biases, perception of problems by this population, economic imperatives and negative perceptions of these patients by orthodontists. The primary objective of this study is to examine the usefulness of early orthodontic intervention as a possible means of increasing access to orthodontic services for children of low-income families. We will examine the effects of early interventions in Medicaid patients using a randomized clinical trial comparing dental, esthetic and psychosocial predictors and outcomes in children who receive early orthodontic treatment and those who do not. This study will also have a follow-up descriptive component, with a matched design, making similar comparisons between Medicaid-funded and privatepay patients receiving full orthodontic treatment at adolescence. Aim 1 will compare orthodontic outcomes, motivations for treatment, expectations from treatment and satisfaction with results between Medicaid participants who receive early orthodontic treatment and those who do not. A sub-aim of Aim 1 will compare, in the Medicaid group receiving early treatment, the level of understanding and compliance between subjects given informed consent using an interactive CD-ROM and those receiving routine consenting procedures given one-on-one by an orthodontist. Aim 2 will compare parameters similar to those in Aim 1 in Medicaidfunded and private-pay patients who receive full orthodontic treatment at adolescence. Aim 3 will compare these same parameters between Medicaid-funded patients who receive early orthodontic treatment only and Medicaid-funded participants who receive full orthodontic treatment at adolescence. Orthodontic outcomes will be assessed using objective, valid and reliable measures of malocclusion and treatment need (i.e., Peer Assessment Rating and Index of Orthodontic Treatment Need). Patient/parent satisfaction, oral health behaviors and values, body image and quality of life will be assessed using instruments that have also been shown to be valid and reliable. It is expected that significantly greater access to orthodontic services could be provided for Medicaid patients by the more widespread use of simpler, more timely interventions. This study will provide data on the trade-off between simple, timely partial treatments aimed at many patients, versus complete full treatments aimed only at the most severely affected patients.